Extractor.watch()

src/background/messaging.ts

@@ -1,6 +1,6 @@
 import { Request, Actions } from "../common";
 import { getTabByID } from "./actions";
-import { caches, logger } from "./common";
+import { logger } from "./common";
 
 /**
  *  Sending a message to target tab repeatedly until the response is not undefined.
@@ -78,14 +78,41 @@ export function sendMessage<T>(
     });
 }
 
-chrome.runtime.onMessage.addListener(function (request: Request, sender, sendResponse) {
-    switch (request.action) {
-        case Actions.UPLOAD_STATE:
-            sendResponse('recieved!');
-            caches.setState(request.fileName, request.state)
-            break;
-        default:
-            sendResponse("Request not supported.");
-            break;
+export type ActionSubscriber = (request: Request, sender: chrome.runtime.MessageSender, sendResponse: (response?: any) => void) => void | Promise<void>;
+class MessageSubscribers {
+    private listeners: { [key: number]: ActionSubscriber[] } = {};
+    addListener(action: Actions, subscriber: ActionSubscriber) {
+        this.listeners[action] || (this.listeners[action] = []);
+        this.listeners[action].push(subscriber);
     }
+    removeListener(action: Actions, subscriber: ActionSubscriber) {
+        this.listeners[action] || (this.listeners[action] = []);
+        for (let i = 0; i < this.listeners[action].length; i++) {
+            if (this.listeners[action][i] == subscriber) {
+                this.listeners[action].splice(i, 1);
+                i--;
+            }
+        }
+        logger.debug(`${this.listeners[action].length} subscriber(s) remained for action ${Actions[action]}`);
+    }
+    getListeners(action: Actions): ActionSubscriber[] {
+        return this.listeners[action]
+    }
+}
+export const messageSubscribers = new MessageSubscribers();
+
+chrome.runtime.onMessage.addListener(function (request: Request, sender, sendResponse) {
+    let subscribers = messageSubscribers.getListeners(request.action);
+    if (!subscribers || !subscribers.length) {
+        sendResponse("Request not supported.");
+        return;
+    }
+    let promises: Promise<any>[] = [];
+    for (let subscriber of subscribers) {
+        let p = subscriber(request, sender, sendResponse);
+        if (p instanceof Promise) promises.push(p);
+    }
+    if (promises.length)
+        return Promise.all(promises);
+    return;
 });